1. Field of the Invention
This invention relates to a semiconductor device manufacturing method and a semiconductor device manufacturing apparatus for manufacturing a semiconductor device by forming a structure film on a substrate in a reaction chamber.
2. Background Art
In a semiconductor device manufacturing apparatus for manufacturing a semiconductor device by forming a dielectric film, conductive film, or other structure film on a wafer, such as an LP-CVD (low pressure chemical vapor deposition) or other film formation apparatus, its use results in deposition of the film formation material on the inner wall of the reaction chamber. When such a deposition film becomes too thick, the deposition film peels off and causes contamination in the reaction chamber, and the condition in the reaction chamber becomes nonuniform by local peeling of the deposition film. This causes the problem of nonuniformity in the thickness and quality of the structure film formed on the wafer.
Thus, for continued use of the film formation apparatus, during intervals between the intended uses for forming a structure film on a wafer, dry etching is regularly performed inside the reaction chamber to remove the deposition film deposited on the inner wall of the reaction chamber (see, e.g., JP-A-2003-077838(Kokai)). For instance, a monitoring wafer is placed in the reaction chamber, and dry etching is performed when the thickness of the deposition film deposited on this monitoring wafer reaches a reference value or more. In this dry etching, a halogen-based cleaning gas, such as HF gas and F2 gas, is used.
However, in this dry etching, accurate endpoint determination is difficult, and conventionally, the etching time is empirically determined. Thus, as the case may be, the deposition film is left on the inner wall of the reaction chamber due to underetching, or conversely, the reaction chamber is damaged due to overetching. The deposition film left on the inner wall peels off and causes contamination in the reaction chamber, and the condition in the reaction chamber becomes nonuniform, thereby decreasing the yield of the semiconductor device. On the other hand, damage to the reaction chamber results in increasing the replacement frequency of components of the film formation apparatus. Thus, in either case, the productivity of the semiconductor device is decreased.